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Earthquakes
Term | Definition |
---|---|
Stress | force that acts on rock to change its shape or volume |
Tension | pulls on the crust, stretches rock causing it to become thinner in the middle |
Compression | squeezes and pushes rock together until it folds or breaks |
Shearing | pushes two masses of rock in two opposite directions, can cause masses of rock to slip |
Faults | occur along boundaries, where the forces of the plate motion push or pull the crust so much that the crust breaks |
Hanging Wall | rock that lies above the fault |
Footwall | rock that lies below the fault |
Normal Faults | fault is at an angle, so one block of rock lies above the fault (hanging wall) while the other block lies below the fault (footwall) |
Reverse Faults | caused by compression. They have the same structure as a normal fault, but the blocks move in the opposite direction |
Strike-Slip Faults | rocks on either side of the fault slip past each other sideways, with little up or down motion |
Anticline | a fold in rock that bends upward into an arch |
Syncline | a fold in rock that bends downward to form a valley |
Folded Mountain |